Eberspacher BA-6 gas Heater for sale
fits all vanagon and bus from 68-91
has timer switch,  to pre-heat van, or use while camping (w/ additional battery)  use while driving or short pd.s while parked, no need for aux battery.
from 81 vanagon.  auxilliary heater booster. can work on air or watercooled.
complete w/ all safety switches , wiring etc. whole unit.  $299